1. Technical Field
This invention relates to a magnetic head used in a recording/reproducing apparatus using, as a recording medium, a magneto-optical recording medium such as a magneto-optical disc. The invention further relates to a magnetic head device provided with such a magnetic head, and more particularly to a magnetic head, for use with a magneto-optical recording medium where information signals are recorded, slidably in contact therewith and a magnetic head device provided with such a magnetic head.
2. Description of Related Art
Hitherto, there has been employed a magneto-optical disc recording/reproducing apparatus using, as a recording medium, magneto-optical disc in which a magneto-optical recording layer composed of a perpendicular magnetization film is provided on a transparent substrate (base member) which is transparent to light.
Such a magneto-optical recording/reproducing apparatus has a structure in which an optical pick-up device (unit) for emitting light beams irradiated onto a magneto-optical recording layer is oppositely disposed at one surface side of the magneto-optical disc. The magneto-optical disk is rotationally operated by a disc drive mechanism. A magnetic head device (unit) for applying an external magnetic field to the magneto-optical recording layer is oppositely disposed at the other surface side of the magneto-optical disc.
The magneto-optical disc recording/reproducing apparatus serves to apply a magnetic field in which the direction of the magnetic field is modulated in accordance with an information signal to be recorded from the magnetic head unit to the magneto-optical recording layer of the magneto-optical disc and to converge light beams emitted from the optical pick-up unit to the magneto-optical discs. In this way, portion of the disk is heated beyond the Curie temperature by irradiation of light beams so that the coercive force disappears. The disc can then be magnetized in accordance with the direction of the magnetic field applied from the magnetic head unit. After this magnetization, light beams are moved relative to the magnetized portion of the disc by rotation of the magneto-optical disc so that the temperature is lowered to less than Curie temperature, whereby the direction of the magnetization is fixed. Thus, recording of information signal is carried out.
Meanwhile, in the conventional magneto-optical disc recording/reproducing apparatus, at the time of recording an information signal, a magnetic head is opposed to a magneto-optical disc rotationally operated with a fixed spacing therebetween in such a manner that the magnetic head is not in contact with the magneto-optical disc. The reason why such an approach is employed is to prevent the magnetic head (with a core of metal such as ferrite) from damaging the magneto-optic disc by sliding contact between the magneto-optical disc and the head.
In view of the above, in the conventional magnetic head device, there is provided an electromagnetic control mechanism for allowing the magnetic head to undergo displacement following surface vibration of the magneto-optical disc so that the magnetic head can hold a fixed spacing without being in contact with the magneto-optical disc even in the case where surface vibration takes place. Such contact is prevented even when the magneto-optical disc is rotationally operated, and subject to warp (warpage) and/or unevenness of thickness of the magneto-optical disc.
In the magnetic head device provided with electromagnetic control mechanism for allowing spacing between the magnetic head and the magneto-optical disc to be kept fixed, power for driving the electromagnetic control mechanism is required, leading to increase in power consumption. Further, a detecting mechanism for detecting spacing between the magnetic head and the magneto-optical disc is also required. As a result, not only the mechanism for controlling the magnetic head device becomes complicated, but also the configuration of the recording/reproducing apparatus becomes complicated. Thus, it is extremely difficult to allow the apparatus itself to be small-sized and of 25% thin plate structure.
In view of the above, there has been proposed a magneto-optical disc recording/reproducing apparatus provided with a magnetic head device for carrying out recording of an information signal in the state where the magnetic head is caused to be slidably in contact with the magneto-optical disc. This magnetic head device in slidable contact with the disc replaces the magnetic head device which maintains a fixed spacing from the disc.
As a magnetic head device used in the magneto-optical disc recording/reproducing apparatus of this kind, there is a magnetic head device described in the Japanese Patent Application Laid Open No. 290428/1993 publication.
As the magnetic head device described in the above-mentioned publication, there is a magnetic head device as constructed as shown in FIGS. 1 and 2.
This magnetic head device includes, as shown in FIGS. 3 and 4, a magnetic head 6 composed of a magnetic head element 4 having a magnetic core 1 composed of a magnetic material such as ferrite, etc. and a bobbin 3 on which a coil 8 is wound, and a slidable contact body 5 to which the magnetic head element 4 is attached.
The magnetic core 1 constituting the magnetic head element 4 includes a center magnetic pole core 1a, a pair of side magnetic pole cores 1b, 1b provided on the both sides of the center magnetic pole core 1a, and connecting portion 1c connecting the base end sides of these magnetic pole cores 1a, 1b, 1b. The magnetic core 1 is formed substantially E-shaped as a whole.
The bobbin 3 includes, as shown in FIG. 3, flange portions 3a, 3b at the upper and lower both ends, and is provided with insertion hole 7 through which the center pole core 1a of the magnetic core 1 is inserted in a manner to penetrate through the both flange portions 3a, 3b. At the upper flange portion 3a of bobbin 3, there are provided in a projected manner (hereinafter simply referred to as "projected" depending upon circumstances) a pair of connection pins 9, 9 to which connection terminals of the coil 8 wound between both flange portions 3a, 3b are connected.
By inserting the center magnetic pole core 1a of the magnetic core 1 into the insertion hole 7 to allow the coil 8 to be wound on the periphery of the center magnetic pole core 1a thus to allow the bobbin 3 to be integrated with the magnetic core 1, the magnetic head element 4 is constituted. At this time, a pair of side magnetic pole cores 1b, 1b of the magnetic core 1 are caused to be opposite to each other with respect to the outer circumferential surface of the coil 8 wound on the bobbin 3.
The slidable contact body 5 is formed by molding synthetic material of low friction coefficient, and is provided, as shown in FIG. 3, with a magnetic head attachment (mounting) portion 10 in which the magnetic head element 4 is attached (mounted) on the base end side. A slidable contact portion 11 slidably in contact with the magneto-optical disc from the front end side of the magnetic head attachment portion 10 is integrally formed in a projected manner. At the magnetic head attachment portion 10 provided at the slidable contact body 5, there is provided a fitting recessed portion 12 in which the magnetic head element 4 is fitted and disposed. This fitting recessed portion 12 is formed with the surface side opposite to the magneto-optical disc being as opening end. A fitting hole 13 into which connecting portion 1c of the magnetic core 1 is fitted is bored at the bottom surface portion. Further, at the bottom surface portion, there are bored through holes 14 for allowing connection pins 9, 9 provided at the bobbin 3 to be projected from the slidable contact body 5. As shown in FIG. 3, the through holes 14 bored continuously with the fitting hole 13.
Further, the magnetic head element 4 is attached, as shown in FIG. 4, to the magnetic head attachment portion 10 by allowing the connecting portion 1c of the magnetic core 1 to be fitted into the fitting hole 13 and allowing the connection pins 9, 9 to be projected from the through holes 14 so that they are fitted into the fitting recessed portion 12. At this time, magnetic head element 4 is connected within the fitting recessed portion 12 by means of bond (adhesive agent) so that it is prevented from slipping off from the magnetic head attachment portion 10. Alternatively, there is employed a method in which, which makes use of the fact that the slidable contact body 5 is formed by synthetic resin. Specifically, heat caulking can be used to thermally deform the opening end side of the fitting recessed portion 12, thereby fixing the magnetic head element 4 within the fitting recessed portion 12.
Moreover, the slidable contact portion 11 is provided in such a manner that it is projected from the front end side of the magnetic head attachment portion 10, and is formed in such a manner to swell a slidable contact surface 15 slidably in contact with the magneto-optical disc from the surface opposite to the magneto-optical disc of the magnetic head attachment portion 10. On the upper surface opposite to the slidable contact surface 15 of the slidable contact portion 11, a fitting projection 17 for attaching the magnetic head 61 to a leaf spring 16 for elastically (resiliently) and displaceably supporting it is provided in a projected manner. This fitting projection 17 is projected on a pedestal 18 inclined relative to the upper surface of the slidable contact portion 11 in order that the front end side of the slidable contact portion 11 is projected to the magneto-optical disc side when the magnetic head 6 is attached to the leaf spring 16 as shown in FIG. 2.
The magnetic head 6 constituted as described above is attached, as shown in FIGS. 1 and 2, to a magnetic head attachment (mounting) portion 20 formed at the front end side of the leaf spring 16 of which the base end side is fixedly supported by the head supporting arm 19.
The leaf spring 16 to which the magnetic head 6 is attached is of a structure as shown in FIG. 1 such that there is bored a cut portion 21 to which the magnetic head attachment portion 10 of the slidable contact body 5 in which the magnetic head element 4 is attached facing the front end side is faced, and the magnetic head attachment portion 20 is provided at the front end sides of a pair of supporting arms 22, 22 extending from both sides of the cut portion 21. This magnetic head attachment portion 20 is connected, on both opposites, to the front end sides of the supporting arms 22, 22 through narrow supporting portions 23, 23 adapted to easily undergo elastic (resilient) displacement.
The magnetic head 6 is attached to the leaf spring 16 by allowing the magnetic head attachment portion 10 of the slidable contact body 5 to be facing to the cut portion 21, and allowing the fitting projection 17 projected on the upper surface of the slidable contact body 11 to be fitted into a fitting hole 24 bored in the magnetic head attachment portion 20.
The magnetic head 6 attached to the leaf spring 16 in this way is caused to undergo elastic (resilient) force of the leaf spring 16 so that it can be in contact with the magneto-optical disc. When the magnetic head 6 comes into contact with the magneto-optical disc, the slidable contact portion 11 of the front end side of the slidable contact body 5 first comes into contact with the magneto-optical disc. Then, the magnetic head 6 is caused to undergo biasing force of the leaf spring 16 so that it comes into pressure-contact with the magneto-optical disc. As a result, the supporting portions 23, 23 for supporting the magnetic head attachment portion 20 are deformed in such a manner that they are twisted. Thus, the slidable contact portion 11 of the front end side of the slidable contact body 5 comes into slidable contact with the slidable contact surface in such a manner to follow (become in conformity with) the principal surface of the magneto-optical disc.
In this example, when the slidable contact portion 11 is slidably in contact with the principal surface of the magneto-optical disc in such a manner to follow it, the slidable contact body 5 rotates with the direction perpendicular to the length direction of the leaf spring 16. The supporting portions 23, 23 define the axis of this rotation. For this reason, at one side of the slidable contact body 5, there are projected a pair of rotation limit pieces 25, 25 for limiting the rotational displacement when the slidable, contact body 5 is caused to undergo rotational displacement about the axis defined by the supporting portions 23, 23 and for limiting excessive torsion (twisting) of the supporting portions 23, 23. These pair of rotation limit pieces 25, 25 are extended, as shown in FIG. 2, at upper and lower portions of one supporting arm 22 provided at the leaf spring 16. When the slidable contact body 5 is caused to undergo rotational displacement, the rotation limit pieces 25, 25 come into contact with the supporting arm 22 so that excessive rotation of the slidable contact body 5 is limited.
Meanwhile, power supply to the coil 2 of the magnetic head 6 attached at the front end side of the leaf spring 16 is carried out through a flexible wiring substrate 26 extended onto the leaf spring 16. This flexible wiring substrate 26 is fixed on the leaf spring 16 by allowing an engagement hole 27 to be engaged with a cutting raising piece 26b formed by cutting and raising a portion of the leaf spring 16 so that the cutting raising piece 26b is bent. (folded). In addition, the flexible wiring substrate 26 and the coil 8 are electrically connected by inserting land portions formed at the end portions of wiring patterns 26a formed on the flexible wiring substrate 26 into the connection pins 9, 9 projected on the upper surface of the slidable contact body 5 by soldering thereto.
The magnetic head constituted as described above is fixed by using bond in the case where the magnetic head element is attached to the slidable contact body. For this reason, attachment work for attaching the magnetic head element to the slidable contact body can be troublesome, and also it is difficult to precisely maintain attachment position a accuracy with respect to the slidable contact body of the magnetic head element.
Moreover, in the case where the magnetic head element is attached to the slidable contact body, even in the case where there is employed thermal (heat) caulking method of thermally deforming magnetic head attachment portion to fix it, attachment work for attaching the magnetic head element to the slidable body can still be troublesome.
Further, in the case of the above-described magnetic head, since connection between the magnetic head and the recording control section of information signal is carried out by using the flexible wiring substrate, electric connection between the flexible wiring substrate and the connection pins is carried out by soldering. For this reason, soldering work is required for assembling the magnetic head. As a result, the assembly work can be troublesome, and also rapid assembling cannot be carried out.